Control system for oil burners



June 3, 1930,

D. R. MARTIN CONTROL SYSTEM FOR OIL BURNERS Filed June 1, 1926 INVENTOR. Ja i/zw w A TTORNEY.

' 25 struction.

I Patented June 3,1930

F 'UNITEDLTSTATES PATENT w s 4 ona 1t. MARTIN, or DETROIT, mcnre'an coN'rnor. SYSTEM ran on. nonmms I Application filed June 1,

' functionin any operative part of the machine renders the burner inoperative- There are manycontrol systems that are artially automatic in rendering the burner inoperative and therefore unsafe since oil may continue to be delivered to the burner even though the flame be extinguished. My invention seeks to. provide means that automatically renders the burner inoperative until it is given manual attention incase of nonignition of the fuel, absence of oil due to the tank becoming drained, the flame going out due to momentarywor' contained stoppage in the oil line, .improper combustion; causing a heavy deposit within the combustion chamher, breakage of any operative part of the -machine etc. It is also an object of the invention to provide means for the purpose stated that is com-- paratively simple and inexpensive in con- Apparatus embodying these .various fea-' tures of control and cooperating in the manner stated is shown in the accompanying drawing whichis a sectional view of'an ap paratus embodying my invention and indlcating its general application to control of a fuel oil burner adapted forelectric ignition. As

is hereinafter described, it is to be understood that the general arrangement of the burner and character of ignition may .be varied without departing from the spirit of this invention as set forth in the appended claims.

- In the drawingsv Fig. 1 is a view partly dlagrammatic km 49 form showing the apparatus for thecontr l of the electric circuits. f

Fig. 2 is a View showing an alternative arrangement of clrcuit.

In Fig. 1 the furnace (which may be a,

steam boiler, a hot water or hot air type) is indicated generally at 1 through a wall of which is 'mtroduced the 'nozz e 2 through which air and oil are to be discharged'in theform of a spray and in the construction shown, ignition, is I secured by operation of a spark 1926. Serial No. 113,038.

' plugv 3 "extending to proximity with the v sprayed fuel as it leaves the nozzle. With this character of burner, which is merelv illustrativeof a burner that may be used with my automatic control, an air pump is pro-' 5 vided at 4 which may-be of any desired type operated by an electric motor indicated at 5 and the discharge from the pump is through the conduits 6 and 6 leading to the nozzle 2.

Adjacent-the nozzle, the oil line 7 is intro- 00 duced so that the air being discharged there- 'through draws oil into the air flow which is broken up into a fine spray in passing through 1 the nozzle.- This oil and air supply arrangement is well known, and it is to be understood 05 that any of the various forms of the device for atomizing the oil may be utilized.

With burners of-the general type here shown, the operation is controlled 1 y a thermostat usually placed in the room to be heated and indicated at 8 in the drawing as being 1n the current supply-line. With this ar rangement of apparatus, failure in proper operation of the burner and an unsafe concommon defects are obviated by the control stem hereinafter outlined and a clear unerstanding of'the operation of the device and its automatic control to provide for safety in operation will be evident fromthe following description.

. Adjacent the boiler in any convenient relationship. I provide a casing 9 in which there is an electro-magnet 10 and an 'electro-magnet 11. There is also shown a lever 12 by means of which the current supply circuit may be made or broken. The two electromagnets 10 and 11 are provided respectively with thearmatures 13 and 1&1 and these armatures are both mounted on a lever 15 piv;- otally supported in the casing at 16. The

magnet and its relation to its armature is such that, upon flow of current therethrough, it will lift the armature 13 and lever 'bringing the'armature 14 to approximately contact with the core of the magnet 11.. The magnet 11 is bf such power that .upon current being supplied thereto it can hold the armature 14 subsequent to the lever 15 being lifted by the magnet 10 to the position shown in dotted lines in the drawing. Current is supplied to the magnet 11 through the lifting of the lever 15 to the dotted position by reason ofthe contact 17 engaging its companion 18 which closes the circuit through the magnetll. Operation of theseparts is as follows- Upon demand for heat by the thermostat 8"the circuit is closed across the supply lines 19 and 20 as. follows-The line 19 is connected with the contact 21 through the terminal 38 and line 38 and by reason of the a0 cold furnace .this member 27 is engaged by position of the lever 12 shown by full lines in the drawing, is in electrical contact with the contact member 22 on the said lever. This contact 22 is connected by the line 23 with the terminal 24on the casing. This terminal is connected by means of the line 25 with the magnet 10 and from the magnet 10 is continued a line 26 'to a stationary contact'27 mounted in the casing. Normally with a the movable contact 28 on the stem 29 connected with the bellows member 48. From this movable contact extends the line 30 to' the terminal 33 and thence by line 30 to the ignition transformer 31. From the trans- I former extends the'line-32 to a terminal 33 I to which is connectedathe opposite line 20 of the supply circuit. The completion of this circuit causes current to flow through the magnet 10 raising the armatures13 and 14' and lever 15 to the position shown by dotted lines and closes the motor circuit as follows- From the terminal 33 extends the line 34 to the. magnet 11 and thence by line 35 to the contact 18 which, being closed throu h'operation of the armature lever 15 by t e maginto operation and it is to be noted that the circuit for the spark plug is completed ahead of the operation of the motor and thus the ignition spark is provided previous to discharge of oil through the nozzle. The spark plug circuit is indicated by line 72 and ground line 71 connected with the ignition transformer 31. f

' To prevent continued operation of the mo tor in the event ignition doesnot take place of air from the'line6 to the line 42 is controlled by a needle valve 43 so as to provide for slow accumulation of air under pressure to expand the bellows and provide a time period for expansion of the bellows and the projection of the end of the stem 40 through its aperture in the casing. This time period may be controlled through the setting of the needle valve and should be ample to permit ignition of the fuel. However, should no ignition take place for reasons hereinafter given, the bellows 39 continues to expand through accumulation of pressure of air therein; and the stem 40 is projected to engage a' lug 44 on the weighted lever 45 inthe casing. This lever is shown in its normal position for operation of the burner and the projection this stem 40 to engagement with theqnember 44 moves the lever to past a position vertically over the pivot point 46 so that the gravity causes the lever to fall to a position shown in dotted lines in the figure. The

pressure required to throw the lever 45 is slight as it may be set-in anearly balanced position relative to its pivot. Thus no great pressure is required to be supplied to the bellow s 39. Upon throwing the lever to-the posltlon shown by dotted-lines, a short arm 47 adjacent-the pivot point of the lever engages an end of the pivoted lever 12 raising it to the position shown in dotted lines in the drawing and breaking the contacts-21 and 22 and thus both breaking the motor and ig-' nition circuits and therefore the current supply circuit which; causes cessation of opera tion of the burner.

is not desired and I have therefore provided a means for preventing the throwing ofthe I weighted lever by the stem 40 if the oil is ignited. For this purpose I provide a thermostat which consists of the bellows member 48 mounted in the casing 49 attached to the main casing 9 and having a stem 29 extendmg upwar 1y through an aperture in the mam'casmg V cross mem er'50 statlonarily su ported in the casing 9. The upper end of tfils stem 29 is notched as indicated and may be extended into the ath of travel of the end of the stem 40 as in icated by dotted lines providing a stop for the said stem 40 and preventing it from engaging the lug 44 of the weighted lever '45., This stem 29 is. projected to the stated position by expansion of the bellows member and this is occasioned in the following manner :This bellows member 48 is open at its lower end to the tube 51 which 9 and through an aperture in the causes the bellows to expand and projects the stem 29 into the path of movement of the stem 40. Under this condition the circuit for the motor will not be broken inasmuch as the operation of the burner is normal. The stem 52 extends into the fire box and is open at both ends to provide for fiow of air about the tube 51 to hasten the cooling of the volatile fluid in the event the flame is extinguished. It is also to be noted that a spring 53 is provided tending to contract the bellows 48 but this spring is not of suflicient length to completely collapse the bellows 48,

v subsequent to an expansion thereof, to the point shown in the drawing in which the contacts 27 and 28 are shown as closed. The contact 27 being attached to the stem 29 will on contraction of the bellows approach the contact 27 but the parts are so arranged that the spring will not of itself contract the bellows to such extent and to close the contacts it is required that the volatile liquid in the bellows 48 and 51 become normally cool and reduced to practically original volume. This final contraction of the fluid tends to finally move the bellows to normal position and close the contacts 27 and 28. As these contacts are in the ignition circuit no re-ignition of fuel may take place until the thermostat has cooled to normal condition. It isto be noted that, by having the ignition circuit controlled by movement of the stem 29, once this ignition circuit is closed through operation of the room thermostat it remains closed until the heat of combustion breaks the circuit. This avoids a common source of danger in burners in which the ignition circuit is energized for a predetermined period of time andthen ceases to function. This arrangement provides a double safetyfactor in that it I maintains the ignition. circuit in operation until the heat of combustion breaks the same and if no heat of combustion breaks the circuit the time operated stem 40 will function to break the circuit of the main supply line when both the motor and ignition circuits become dead The energization of the ignition circuit depends upon a flow of current through the magnet 10 and thus if the circuit Lo the said magnet'lO is broken the apparatus Will not function through closing of the main circuit by the room thermostat 8. The circuit Wires therefore must be intact and the contacts 27 and 28 made and the thermostat tube 51 must be practicallv cold before there is possibility of energization of the ignition circuit.

where there is insufficient air supplied for combustion. Under such condition there will beproduced an accumulation of soot in the An undesired condition occurs in a furnace fire box and flue for the furnace which becomes a fire hazard as this soot contains more or less oil and may ignite. If soot has accumulated in this fire box the burner will not recycle upon being shut off in the normal way by the room thermostat because the end of the tube 51 within the furnace is heavily coated with soot which is an insulator and therefore will not absorb heat quickly enough to expand the bellows 4-8 and position the end of the stem 29 in front of the stem 40 and permits throwing the weigh-ted lever 45 and breaking the circuit through operation of the lever 12. Likewise if the flame goes out through stoppage of oil flow there is no reignition under such condition due to the fact that the ignition circuit stands broken at such interval through the expansion of the bellows 48. i The stoppage of oil flow and cessation of flame in the furnace will cause the bellows 48 to contract as heretofore stated and no closing of the ignition circuit may take place under this condition unless the volatile fluid in the tube 51 and bellows 48 have cooled Another source of improper operation of the burner is caused through failure of the room thermostat to break the supply circuit at the predetermined room temperature. Under such condition the burner continues to operate at its full capacity and overheating of the room's results and possibly other conditions arise that are a source of danger that is, an overheating of the furnace. To guard against such failure of the room thermostat I have provided a safety element which consists of a bellows 60 mounted on the casing 9 and provided with a stem 61. This bellows member may be directlyconnected by means of a tube 62 with the steam space of a boiler or, as is common practice, a tube for volatile fluid (not here shown) may be introduced in the upper part of a furnace structure which leads through a tube 62 to the bellows member. Upon an exlot i lie cess of heat causing more than the usual steam pressure for the line 62 (or evaporation of volatile fluid in the tube if such tube be utilized), the bellows member 60 is expanded moving the stem 61 to engagement with the member 12 which will raise the same to separate the contacts22 and 21 and break the main circuit. M

It will be evident from the foregoingdescription that in the normal operation of the device in control of the burner, the burner will be operated upon demand for heat through operation of the room thermostat 8 and the burner will cease to operate when. the demand for heat is satisfied. The burner will cease operating if the steam pressure or the temperature of a hot water or hot air furnace exceeds a certain predetermined degree and this result is secured if the tem-, perature or'pressure reaches a predetermined point before the thermostat demand is satisfied or if the thermostat 8 sticks and maintains the circuit closed.

Under the normal operation of the room thermostat the burner is turnedon and then off through the permissible variation in temperature of the room and if the burner is turned off through operation of the member 60 it will again be turned on and /will continue to recycle by the "breaking and makingof the main supply circuit through:

operation of the lever 12. If an electric. ignition is utilized the circuit for the spark plug is closed every time the burner is turned on and is broken as soon as the fuel becomes ignited and this breaking of the spark plug circuit occurs within a period of approximately fifteen seconds through the application of heat to the volatile fluid, tube 51.

Under abnormal conditions the operation of the device is as follows :-If the supply current is dlscontlnued for some cause 1n the It is main supply line and then comes on again after lnterruption While the room thermostat is still set to demand heat, the burner will start andthe apparatus will continue to recycle throughsuchstoppages until the thermostat demand for heat is satisfied. The entire'machine will be rendered inoperative until given manual attention in case of nonignition, depletion of oil'supply, a stoppage in the oil line (momentary or continued), im-

' proper combustion resulting in the coating of carbon or. breakage in any of the operative parts of the control system, and further will cause cessation of operation of the burner until properly recycled in caseaperson willfullyofperates the room thermostat manually and rapidly from on to otf position. Under this condition cessation of operation 'of the burner will arise as follows- If the thermostat is on and the burner in operation the bellows member 48 is expanded and the ignition circuit stands broken.- Turning to an off position manually of the thermostat 8 will break the motor circuit, Immediately turning the thermostat to on position manually Wlll then not energize the motor circuit because that circuit must initially be connected with the current supply circuit through energization of the lines 26 and 30 and contacts 27 and 28 which stand broken by the bellows member 48. The apg'manu ally operated to break the main circuit, the burner is immediately rendered inoperative until it recycles in a normal way.

The terms main supply circuit or current supply circuit refer to the source of current supply which includes the lead in wire 19, terminal 38, line 38, contacts 21 and 22, line 23 to terminal 24 and the opposite lead in wire is the line 20 to terminal 33 in which is positioned the thermostat 8. There are two paths by which a circuit may be completed across the terminals 24 and 33, the first of which is as follows :-terminal 24, line 25, magnet 10, line 26, contacts 27, 28, line 30, terminal 33*, line 30, to primary of the transformer 31, line 32 to terminal 33 a'ndthis circuit is initially energized through operation of the thermostat 8 of the lead line 20. The second path across these terminals is a terminal 24, line '39" to motor, line 39 terminal 37, line 36, contacts 17 and 18, line 35, magnet 11, line 34 to the terminal 33.

In the preceding description the lines 24 respectively are referred to as a motor circuit but this in fact forms part of what is termed the second path which is normally further to be noted that the thermostat 8 and contacts 21 and 22 on the switch 12 are in thelead in wires and not in either of these paths and thus are positioned to control both said paths and that the switch which includes the terminals 27 and 28 is in what has been termed the first path and controls it dnly, and that the second path includes a switch having contacts 17 and 18 which controls the second path only.

This control system is applicable to the control of a burner system using a pilot flame for ignition as shown in'Fig. 2 and in such case there is no need of use of an ignition transformer or the ground connection 71 and line 72 for the spark plug. Therefore, as suggested, I connect the terminals 33 and 33 by a line 73. With this slight rearrangement the control system is entirely automatic. Instead of the line 30 running to the ignition transformer it connects with the line '20 through this line 73 and the bellows member 48 operates to break this circuit by separation of the contacts 27 and 28 asinthe previous case. If the pilot flame goes out the operation of the device is the same as though the spark plug is inoperative-that is, no ig- 3'9 and 39 connected with the terminals 37 and nition results andthe burner is held inoperaually reset after failure to operate by thesetting of the lever 45 to the position shown in full lines in the figure. This manual resetting, however, will only cause recycling in the event there is no breakage in any of the parts by a momentary cessation of function. While I have shown aconstruction in which the air for combustion purposes is supplied under pressure and providing oil through aspiration the device will function as well if the oil is pumped in under pressure and air is drawn in by aspiration. Under this condition the lines 6 and 42 will be filled with oil under pressure and the line 7 will open to atmosphere. The function of the control parts will remain the same under either condition.

The essential characteristics of a device embodying my invention reside in the provision wit-h electrically operating means for atomizing fuel with air in the furnaceand ignition means therefor, of an element responsive to excess temperature or.- pressure to break the main electrical circuit of the apparatus. This element guards against an overheating of the furnace and prevents operation of the burner to an undesired extent in the event the thermostat in the main line becomes frozen and closes the main circuit.

A second safety factor in my arrangement of the parts is found in means for renderlng the system inoperative in the case of nonignition of the fuel or the flame becoming extinguished. This is accomplished through what may be termed a pressurestat to which pressure of fluid either oil or air is delivered to an expansible bellows in predetermined rapidity of flow providing a specific time period of operation of the burner before the apparatus may be rendered inoperative through actuation of' the pressurestat and, in the event of normal ignition or operation of the burner and continuation of flame, a provision bf means for preventing operation of the pressurestat which, when permitted to operate, renders the apparatus inoperative through the throwing of the main line switch.

with which the first named heat responsive element is in operative relation.

A third safety factor is provided by the use if two electro-magnets, the first of which is directly in the circuit closed by the room thermostat and operates to -close the main circuit through the second electro-magnet which then operates to maintain the said circuit closed and therefore permitting the circuit to the first magnet to be broken through influence of heat of combustion in the fire box without breaking the circuit for the motor but which, in the case of electric ignition, breaks the ignition circuit. By such arran ement it is impossible to start operation of t 1e burner through demand for heat by the room thermostat if the temperature of the fire box is sufficient to break the circuit through the first magnet. Through such arrangement of parts the possibility of faulty and unsafe burner operation is prevented.

Having thus fully described my invention, what I claim and desire to secure by Letters Patent of the United States is 1. A control system for oil burners comprising the combination with the burner and electrically operated means for supplying fuel thereto, of a source of current supply including lead in Wires each extending to terminals, a thermostat in one of the lead in wires for controlling thesupply' of current to said electrically operated means, there being two paths through whichthe supply circuit may be completed, one of which is normally closed and includes means for completing the other and the other of which includes the said electrically operated means, means caused to operate in a predetermined time period by the closing of the supply circuit through the second of said paths to break the supply circuit, a heat responsive device operating by influence of the heat of means providing fuel for combustion, of a supply circuit therefor comprising two leadin wires and terminals therefor, a thermostatfor making or breaking one of said lines through variation in temperature, a normally closed make and break switch in the other'of said lead in lines, there being two paths through which the circuit may be completed across the terminals, a make and break device in each of said paths, the first of said paths being normally closed and the second path being closed through energization of the first path, said second path supplying current to the electrically operated means, means responsive to the heat of combustion vfor breaking the first path, and means controlled through operation of the said electrically operated means for breaking the normally closed switch in the event the said first path is not broken. p t

3. A control system for oil burners for furnaces comprising the combination with the furnace, the burner, an electric motor,

' ply circuit comprising .35

mally broken,

trically operated and means operated thereby providing fuel for combustion, of a current supply circuit comprising two lead in lines and terminals therefor, .there being two paths by which the circuit may be completed across the terminals in one of which the motor is included, a thermostat in one of said lines for making and breaking the same through variation in temperature, a gravity closed switch in the other of the said lead in lines, a make and break device in each path, means responsive to the heat of combustion adapted to break the circuit through the first path, means adaptedto open the said gravity closed switch, said means operating by gravity subsequent to actuation to hold the switch open and requiring to be manually reset to restore the parts to operative relation, a device operated by pressure of the fuel supply means to actuate the switch opening means, means caused to operate through closing the supply circuit through the first path to close the said second path and energize the motor circuit, and means whereby operation of the heat responsive device in breaking the first path prevents actuation of the switch opening means.

4. A control system for oil burners for furnaces comprising the combination with the furnace, the burner, an electric motor and means operated thereby for discharging fuel and air to the burner, one of said. elements being discharged under pressure, of a supterminals therefor, a thermostat operating through variation in temperature to open and close one of said lines, the said supply circuit having twopaths through which it may be closed, the motor, being energized through one of said paths, a make and break device in each of the saidpaths, a heat responsive d'evice normally holding the first path closed and the second path being nora magnet in the first path energized through the closing of "the circuit through the first path to close the second path, a magnet energized on the closing of the second path to hold the said second path closed through the'motor, means responsive to pressure of the fuel supply means caused to be moved in a predetermined time period to break the supply circuit, means whereby operation of the heat responsive device breaks the said first path and prevents the breaking of the supply circuit by the pressure responsive means, and an ignition circuit for the burner closed when the first path is closed,

5. A control system for oil burners for furnaces comprising the combination with the furnace having a fife box, a nozzle and elecmeans for discharging fuel and air through the said nozzle, one of the said combustion elements being under pressure, of electric means for ignition of two lead lines and' the fuel at the nozzle, a current supply circuit comprising two lead lines and terminals therefor and two current paths between the terminals, a thermostat in one of the said lead through the first path, a device responsive to the pressure developed in one of the said combustion elements tending to break the circuit, said device responsive to the heat of combustion being adapted to prevent operation of the said pressure responsive device to break the circuit, additional means tending to break the said last named lead line upon excess heat developed in the furnace, and means caused to break the circuit through the electrically operated means by cessation of current flow therein,

6. A control system for oil burners comprising in combination with the furnace, burner and electrically *operated means for supplying fuel and air to the burner for combustion, one of said combustion elements being under pressure, of a current supply circuit having two paths through which it may be completed, a thermostat in the said supply circuit for opening and closing the same, a spark plug for igniting the fuel, a circuit for the spark plug including a transformer coupled with the first path, a make and break device in each of the said two paths, means energized by current flow through the first path adapted to complete the second path, an electric motor and circuit therefor included in the said second path, a switch in the, said supply circuit, a lever for opening the switch and tending vto act by gravity to'hold the switch open and to be held by gravity in position to leave the switch closed, a device responsive to pressure developed in one of the said combustion elements to turn the lever to position to be actuated by gravity to open the switch, means responsive to the heat of combustion for preventing the pressure responsive device from and ignition circuit may be energised or de energized, means whereby completion of the supply circuit through the first path causes completion of the circuit through the second path, means caused to operate in a predetermined time'period through energization of. the second path including the motor to break the supply circuit, a heat responsive device operating through influence of the heat of combustion to prevent breakage of the supply circuit by the time operated'element, means whereby operation of said heat responsive device breaks the said first path, means in the'said second path for maintaining the current supply circuit closed therethrough as long as current is supplied and for breaking thecircuit upon failure of said current. 1

' 8. A control system for oil burners comprising the combmation with the burner and an electric motor for providing fuel for combustion, of a current supply circuit, a thermo stat in the said circuit for making and breaking the same, said circuit having two paths through which it may be completed the first of which is normally closed, said first path being directly connected with the terminals of the supply circuit whereby the closing of the supply circuit by the thermostat energizes the said first path, means whereby energization of the supply circuit and' the first path causes completion: of the supply circuit through the second path, said electric motor being included in the said second path, a switch said supply circuit, means caused tooperate'through completion of the supply circuit through the second path adaptedtd open the switch in a predetermined time period, and a heat responsive device operating through accumulation of heat from com ustion to prevent said switch operation and through lack of heat to allow said time operated means to open said switch. 7

' 9. A safety control system for-oil burners comprising the combination with the burner and an electric motor for providing fuel for combustion, of a current supply circuit a thermostat in the said circuitadapted through varlation in temperature to open and close the'circuit, said supply circuit having two paths through which it may be completed, a switch in said supply circuit adapted to open and close the saine, the first of said I paths being normally closed and the second path including the motor, a device caused to move through energization of the said-second path to open the saidswitch in the event .of

failure of combustion, .means operating in the event combustion occurs to prevent open-, 1

ing of the said switch, means responsive to excess heat application by the burner to inated by the motor, of a current supply circuit 7 having two paths through which it may be completed the first of which it normally closed, a thermostat in that part of the supply circuit not included in either of said paths, an electric ignition device and circuit therefor included in the first path, the motor being included in'the second path, a normally closedswitch in said supply circuit, a furnace safety device actuated at a predeterminedhigh furnace temperature to open the switch and arranged to allow the switch to close upon the furnace temperature falling to normal, means energized by current fiow'through the first path adapted to close the second path,

means in the said second path for maintaining the same closed as long as current is supplied and adapted to break the said path I through failure of current flow therein, means operated through energization of the motor to independently open the switch and adapted to hold the switch in the open position until manually closed, and means responsive to the heat generated by the burner to prevent said means from opening the switch, said last named means being adapted upon opera-' tion to break the supply circuit through the first path. v v e 11. A control system for oil burners comprising the combination with the burner and electrically operated means for providing fuel for'combustion, of a source of current supply for said electrically operated means comprising a pair of wires leading to terminals individual thereto, a thermostat in one of the said wires operating through variation in temperature to open or close the same, a nor 1 movable through,energization of the electri- 'cally operated means to open the? said normally closed switchgin a predetermined time period, a heat responsive device operating to obstruct the movement of said movable completed across the said terminals, meansthrough influence ofthe heat of combustion IOU means and-prevent opening of the switch, and means caused to operate through failure I derv the system electrically inoperative until restoredto normal condition.

tion."'. v

- DORR R. MARTIN.

dependently open the said switch and permit the switch to again close when the applied i heat is restoredto normal, and means caused to operate through failure of current in the I In testimony whereof I sign this.specifica-. 

